Lubricant applying system for a rolling bearing

ABSTRACT

In a lubricant application system, a prescribed volume of lubricant is transferred from a lubricant discharge port  8  of a prescribed liquid volume discharge device to a rolling element  703  of a rolling bearing  700  in a state in which the lubricant discharge port  8  is positioned directly above and sufficiently close to the rolling element  703,  whereby the lubricant is applied to the interior of the rolling bearing  700.  Further, the application system inspects whether or not a prescribed volume of lubricant is injected from the discharge device for injecting a lubricant into the interior of a rolling bearing  700.

This is a divisional of application Ser. No. 09/471,232 (ConfirmationNo. Not Assigned) filed Dec. 23, 1999, now U.S. Pat. No. 6,477,885, thedisclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a lubricant applying system for arolling bearing, in particular, an apparatus for applying a lubricant tothe interior of a rolling bearing, and an apparatus for inspecting alubricant applied condition of a rolling bearing adapted to inspectwhether or not a lubricant is applied to the interior of the rollingbearing.

2. Description of the Related Art

FIG. 15 shows the construction-of a rolling bearing. In the figure,reference numeral 700 denotes a rolling bearing, which is constituted byan outer race 701, an inner race 702 and a crown-shaped retainer 704provided between the races for retaining a plurality of ball-likerolling elements 703.

Known as a conventional method for applying a lubricant to the interiorof thus rolling bearing 700 is describes an oil plating method forslightly applying a lubricant on a bearing raceway surface (JapanesePatent Unexamined Publication No. SHO 64-46011), a method including thesteps of dipping the assembled rolling bearing 700 in a lubricant,picking up the rolling bearing 700 from the lubricant and removing thelubricant therefrom in a centrifugal fashion (Japanese Patent UnexaminedPublication No. HEI 8-303467), or a method including the steps ofdipping the rolling bearing 700 in a lubricant diluted with a solvent(petroleum benzine) and thereafter allowing the solvent to evaporate(Japanese Patent Unexamined Publication No. HEI 5-149343).

Widely adopted as a means for assembling the rolling bearing 700 to anapparatus is a method for adhering a radially inner surface of the innerrace 702 to a shaft or for adhering a radially outer surface of theouter race 701 to a housing. In these methods, the adhering surfaces ofthe rolling bearing 700 are required to be dry (hereinafter, describedas a first case).

In addition, in an apparatus such as a hard disk drive in which a highdegree of cleanness is required in the interior thereof, the volume oflubricant component-running out of or flying from the rolling bearing700 needs to be as little as possible. This requires a flat portion aswell as the radially inner and outer surface portions of the rollingbearing 700 to be sufficiently dry. Moreover, if there is some lubricantadhering to a sealing groove portion formed in the outer race 701 andthe inner-race 702, this adhering lubricant runs out of the sealinggroove portion when a seal is inserted thereinto, and therefore thissealing groove portion also needs to be sufficiently dry (hereinafter,described as a second case).

Furthermore, a fiber constituent contained in grease as a lubricant isnot too good to reduce and stabilize the torque of the rolling bearing,and therefore there are some rolling bearings 700 in which grease isrequired to be put on the retainer 704 in order to reduce and stabilizethe torque thereof. In this case, when some of the lubricant requiredfor lubrication in an initial stage (oil component in the grease runsout thereof soon after the initial stage and this oil componentcontributes to the lubrication of the rolling bearing) adheres to theportion where grease is put, the grease becomes easy to slide down overthe retainer 704, and it moves and comes to adhere to rolling elementraceway surfaces of the outer and inner races 701, 702 while the rollingbearing 700 is rotating. Therefore, the torque is increased and causedto vary. In order to prevent this, no lubricant has to adhere to theportion of the retainer 704 where grease is put (hereinafter, describedas a third case).

In addition, there is a case where any combination out of the abovethree cases simultaneously constitutes a problem. In other words, aproblem is caused by a combination of the first and second cases, thefirst and third cases, or the second and third cases. Moreover, there isa case where the first, second and third cases simultaneously constitutea problem.

Namely, it is important that no lubricant adheres to any portion in theinterior of the rolling bearing 700 that does not really needslubrication. What needs lubrication in the interior of the rollingbearing 700 are the rolling element raceway surfaces of the outer andinner races 701, 702 and the surface of the rolling elements 703.

In the aforesaid conventional example, however, it is not possible toapply a lubricant oily to portions in the interior of the rollingbearing 700 which need lubrication and it is unavoidable that arelatively large volume of oil component adheres to portions in theinterior of the rolling bearing 700 other than those that really needlubrication. In addition, in the above-described conventional example,it is very difficult to dry only the exterior of the rolling bearing 700with a needed volume of lubricant being left in the interior thereof.Moreover, manual removal of oil component adhering to the exterior ofthe rolling bearing 700 causes an increase in costs.

Moreover, it becomes important to inspect whether or not a lubricant isinjected into the interior of a rolling bearing through a totalinspection for judgement of defective or non-defective. However, in themethods described in the aforesaid publications, only the process ofapplying the lubricant is described and none of the methods describestherein a process of inspecting a lubricant-applied condition of therolling bearing after the lubricant is applied thereto. Thus, there iscaused a problem that whether or not the lubricant is properly appliedto the completed rolling bearing is unclear.

SUMMARY OF THE INVENTION

The present invention was made in view of the aforesaid problemsinherent in the related art, and an object thereof is to provide asystem for easily and securely applying a lubricant only to portions inthe interior of a rolling bearing which really need lubrication andfurther for inspecting the lubricant applied condition of the rollingbearing by optical detection.

With a view to attaining the above object, according to a first aspectof the present invention, there is provided a method for applying alubricant to a rolling bearing by using a prescribed liquid volumedischarge device comprising at least one discharge port, the methodincluding the steps of placing the discharge port directly above andsufficiently close to a rolling element of the rolling bearing, andtransferring a prescribed volume of the lubricant from the dischargeport to the rolling element for application of the lubricant to theinterior of the rolling bearing.

Further, according to a second aspect of the present invention, there isprovided a method and apparatus for inspecting a lubricant appliedcondition of a rolling bearing adapted to inspect whether or not aprescribed volume of lubricant is discharged from a lubricant dischargedevice for injecting a lubricant in the interior of a rolling bearing. Alaser beam is irradiated between a discharge port of the lubricantdischarge device and the rolling bearing, and a reflected laser beamreflected by a lubricant when the lubricant is discharged from thedischarge port is received by a photoreceptor device disposed on anoptical axis of the reflected laser beam, whereby whether or not thelubricant is applied to the rolling bearing is inspected based on anoutput from the photoreceptor device.

In the method and apparatus for inspecting a lubricant applied conditionof a rolling bearing, when the lubricant is injected into the interiorof the rolling bearing from the discharge port of the lubricantdischarge device, for instance, while a ball of the rolling bearing iscaused to approach to a distal end of the discharge port and then thelubricant is discharged, the laser beam is irradiated between thedischarge port and the rolling bearing, and the reflected laser beamreflected by the lubricant is received by the photoreceptor device.Since the photoreceptor device is disposed on the optical axis of thereflected laser beam, in a case where a prescribed volume of thelubricant is not discharged, the reflected laser beam is reflected in adifferent direction or there is reflected no laser beam, whereby thephotoreceptor device receives no light. Thus, the output variesdepending on whether or not there is reflected a laser beam, andtherefore whether or not the prescribed volume of lubricant isdischarged can be judged based on the output from the photoreceptordevice, whereby the lubricant applied condition of the rolling bearingcan be inspected.

Raised as a specific inspection device for carrying out the above methodfor inspecting a lubricant applied condition of a rolling bearingaccording to the present invention is an inspection device forinspecting a lubricant applied condition of a rolling bearing whichcomprises a discharge device for injecting a prescribed volume oflubricant into the interior of the rolling bearing, a laser beamprojector for irradiating a laser beam between a discharge port of thedischarge device and the rolling bearing, and a photoreceptor disposedon an optical axis of a reflected laser beam produced when the laserbeam from the laser beam projector is reflected by the lubricant forreceiving the reflected laser beam, whereby whether or not the lubricantis applied to the rolling bearing is inspected based on an output fromthe laser beam receptor.

In this device for inspecting a lubricant applied condition of a rollingbearing, when the prescribed volume of lubricant is injected into theinterior of the rolling bearing by the discharge device, the laser beamis irradiated between the discharge port of the discharge device and therolling bearing by the laser beam projector, and the reflected laserbeam produced when the laser beam from the laser beam projector isreflected by the lubricant is then received by the laser beam receptor.In other words, in a case where the prescribed volume of lubricant isdischarged, the reflected laser beam from the lubricant is detected,while in a case where the prescribed volume of lubricant is notdischarged, the reflected laser beam is oriented in a differentdirection, there-being no reflected laser beam that can be detected bythe photoreceptor.

In addition, since the reflected laser beam enters the laser beamphotoreceptor only when the lubricant is discharged from the dischargedevice, after the completion of discharge there is no reflected laserbeam that can detected by the laser beam photoreceptor. Thus, the outputof the laser beam photoreceptor only exhibits a large momentaryvariation in level thereof. Since a momentary variation in output levellike that has to be detected with high sensitivity, it is desirable tointerpose a peak hold circuit to thereby securely detect the output ofthe photoreceptor that is to vary when the reflected laser beam isreceived by the photoreceptor.

Furthermore, the discharge of the lubricant from the discharge deviceinto the interior of the rolling bearing and inspection of a lubricantapplied condition may be carried out sequentially for individual ballsor at one time for the respective balls. In a case where the dischargeor inspection is carried out at one time for the respective balls, arepresentative inspection of a lubricant applied condition may becarried out only for one ball, this helping simplify the inspection.

Although the laser beam projector and laser beam photoreceptor may bedisposed separately in order to increase the degree of freedom ofdesign, they may be integrated into one construction in order tosimplify operations of assembling and regulating of the inspectiondevice.

Furthermore, the following are raised as other methods and apparatus forinspecting a lubricant applied condition of a rolling bearing.

Namely, there are provided a method and apparatus for inspecting alubricant applied condition of a rolling bearing adapted to inspectwhether or not a prescribed volume of lubricant is discharged from alubricant discharge device for injecting a lubricant into the interiorof the rolling bearing, wherein a substance is added to the lubricantwhich emits fluorescence when excited with an ultraviolet ray, whereinan ultraviolet ray is irradiated to the rolling bearing while cuttingoff external light, wherein an image of the rolling bearing to which theultraviolet ray is so irradiated is picked up and wherein a lubricantapplied condition is inspected based on the existence of fluorescencereflected in the picked-up image.

In this method and apparatus for inspecting a lubricant appliedcondition of a roller bearing, since the lubricant applied surface emitsfluorescence when the prescribed volume of lubricant is discharged andapplied to the rolling bearing, it is possible to quickly inspect thelubricant applied condition of the rolling bearing by detecting thefluorescence so emitted.

As an additive emitting the aforesaid fluorescence, for instance, anantioxidant of amine system may be used which does not damage thelubricating properties of the lubricant used.

Provided as a specific inspection device for carrying out the abovemethod for inspecting a lubricant applied condition of a rolling bearingaccording to the present invention is an inspection device forinspecting a lubricant applied condition of a rolling bearing which isadapted to inspect whether or not a prescribed volume of lubricanthaving added therein a substance adapted to emit fluorescence whenexcited with an ultraviolet ray is discharged from a lubricant dischargedevice for injecting the lubricant into the interior of the rollingbearing and comprises a light cut-off hood for cutting off externallight so that the rolling bearing to be inspected is not exposed to theexternal light, a black light provided inside the light cut-off hood forirradiating an ultraviolet ray to the rolling bearing and a video camerafor picking up an image of the rolling bearing irradiated with theultraviolet ray by the black light, whereby the lubricant appliedcondition is inspected based on the existence of fluorescence reflectedin the image picked up by the video camera.

In this inspecting device, in a case where the prescribed volume oflubricant is applied to the rolling bearing, the fluorescence isreflected over a predetermined area in the picked up image when an imageof the rolling bearing irradiated with the ultraviolet ray by the blacklight is picked up by the video camera, while in a case where theprescribed volume of the lubricant is not applied to the rollingbearing, an area reflecting the fluorescence is less than thepredetermined area, or there is no fluorescence reflected in the pickedup image. Thus, whether or not the prescribed volume of the lubricant isdischarged from the lubricant discharge device is inspected based on thefluorescence reflecting area.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view showing the construction of a lubricant applyingapparatus for use in carrying out a lubricant application methodaccording to a first embodiment of the present invention;

FIG. 2 is a side view showing the construction of a oil feed nozzleportion of the lubricant applying apparatus according to the firstembodiment;

FIG. 3 is a block diagram showing the system construction of a controlsection of the lubricant applying apparatus according to the firstembodiment;

FIG. 4 is an enlarged view showing the detailed construction of aportion circled by Circle X in FIG. 1;

FIGS. 5A and 5B are side views showing the construction of a mainportion of a lubricant applying apparatus for use in carrying out alubricant application method according to a second embodiment of thepresent invention;

FIG. 6 is an enlarged view corresponding to FIG. 4 and showing alubricant applying apparatus for use in carrying out a lubricantapplication method according to a third embodiment of the presentinvention;

FIG. 7 is a side view showing the construction of a lubricant applyingapparatus for use in carrying out a lubricant application methodaccording to a fourth embodiment of the present invention;

FIG. 8 is a partially sectional and cut-away view as viewed from adirection C in FIG. 5 showing a lubricant applied condition inspectingapparatus according to a fifth embodiment of the present invention;

FIG. 9 is a plan view as viewed from a direction D in FIG. 5 showing thelubricant applied condition inspecting apparatus according to the fifthembodiment;

FIG. 10 is a block diagram showing the construction of the lubricantapplied condition inspecting apparatus according to the fifthembodiment;

FIG. 11 is a chart showing wave forms of a lubricant dischargingoperation signal, the output voltage of a laser beam photoreceptor andthe output voltage of a peak hold circuit;

FIG. 12 is a diagram showing the construction of a laser sensor for alubricant applied condition inspecting apparatus according to a sixthembodiment of the present invention;

FIG. 13 is a diagram showing the construction of a lubricant appliedcondition inspecting apparatus according to a seventh embodiment of thepresent invention;

FIG. 14 is a block diagram showing a flow of signals for inspecting alubricant applied condition according to the seventh embodiment; and

FIG. 15 is a plan view showing the construction of a rolling bearing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Respective embodiments of the present invention will be described withreference to FIGS. 1 to 14. In addition, a rolling bearing 700 havingthe construction shown in FIG. 15 is used in respective embodiments forexplanation of a rolling bearing to which a lubricant is to be applied.

[First Embodiment]

First, referring to FIGS. 1 to 4, a first embodiment of operation of thepresent invention will be described.

In FIG. 1, reference numeral 1 denotes a prescribed liquid volumedischarge device, which has a plunger pump main body 2. A lubricant tank4 is attached to a liquid suction port 3 connected to a side portion ofa distal end (a lower end in FIG. 1) of the plunger pump main body 2. Inaddition, an oil feed nozzle 6 is attached to a nozzle connecting port 5provided so as to protrude from a distal end face (a lower end face inFIG. 1) of the plunger pump main body 2. As shown in FIG. 2, a pluralityof oil feed pipes 7 are attached to a distal end face (a lower end facein FIG. 1) of the oil feed nozzle 6 in such a manner as to correspond tothe arrangement of rolling elements 703 of the rolling bearing 700. Anoil repellent treatment is carried out on radially outer surfaces of theoil feed pipes 7 for preventing lubricant from adhering thereto. Iflubricant adheres to the radially outer surface of the oil feed pipe 7,there may be caused a case where the lubricant so adhered then adheresto a flat portion or a sealing groove of the rolling bearing 700 orwhere the amount of lubricant to be applied becomes unstable. The oilrepellent treatment can prevent the above problem.

A distal end of the oil feed pipe 7 constitutes a lubricant dischargeport 8. The diameter of a circle (pitch circle) passing between therespective lubricant discharge ports 8 substantially equals to the pitchdiameter of the rolling elements 703 of the rolling bearing 700, andcircumferential angular intervals each of the lubricant discharge portsand the rolling elements 703 are also set to become similar to eachother. The lubricant discharge port 8 is designed to discharge aprescribed volume of lubricant every time. The number of lubricantdischarge ports 8 is determined depending on the discharge volume andviscosity of a lubricant used or the like.

The rolling bearing 700 is set above a rotating device (rotary drivingsection) 9. The rotating device 9 is designed to rotate the rollingbearing 700 around an axial center thereof relative to the lubricantdischarge ports 8. The rotating device 9 includes a base table 10 and arotating table 11 rotatably provided on the base table 10. A holdingportion 12 is provided on the rotating table 11, and the rolling bearing700 is detachably held at the holding portion 12.

In a state in which the rolling bearing 700 is held at the holdingportion 12 of the rotating table 11, the central axes of the rollingbearing 700 and the rotating table 11 are coincident with each other,and these axes are coincident with the central axis (pitch circlecenter) of the arranged oil feed pipes 7.

The prescribed liquid volume discharge device 1 is set on a verticallyslidable table (not shown), so that the discharge device 1 can be movedwithin a predetermined range in directions in which the lubricantdischarge port 8 comes close to and goes away from the rolling bearing700 held at the holding portion 12 of the rotating table 11 (shown inarrows A and B of FIG. 1).

Reference numeral 13 denotes a sensor for detecting the rotatingelements 703 of the rolling device 700. The sensor 13 is set and fixedat a position where it can detect the rolling elements 703 of therolling bearing 700 while the rolling bearing 700 is being rotated onthe rotating table 11.

A relative position of the arrangement phase between the sensor 13 andthe oil feed pipes 7 is set such that the sensor 13 is positioneddirectly below the rolling element 703 when the sensor 13 detects therolling element 703. The rotating table 11 of the rotating device 9 iscontrolled such that it stops when the sensor 13 detects the rotatingelement 703.

When the sensor 13 detects the rolling element 703 of the rollingbearing 700, the lubricant discharge port 8 is located directly abovethe rolling elements 703 by a phase regulation unit, which will bedescribed later, based on the results of the detection to thereby bepositioned relative to each other. Thus, automatic positioning of thelubricant discharge port 8 can be effected.

In this connection, as to the method for positioning the rollingelements 703 of the roller bearing 700, the outer race 701 may be fixedwith a fixture (not shown) and the inner race 702 may be rotated so thatany of the rolling elements 703 is moved to be positioned directly belowthe oil feed pipes 7, or the inner race 702 may be fixed, while theouter race 701 may be rotated. Moreover, a method may be used in whichthe entirety of the fixture is rotated together with the bearing. Inaddition, a method may also be used in which the oil feed pipes 7 aremoved.

A discharge volume regulating mechanism 14 is provided on a proximal endface (an upper end face in FIG. 1) of the plunger pump main body 2. Thedischarge volume regulating mechanism 14 is intended to regulate thedischarge volume of lubricant from the lubricant discharge port 8. Inaddition, air supply pipes 15, 16 for a plunger driving pneumaticcylinder are attached to a portion of the proximal end side of theplunger pump main body 2. When the air supply pipe 15 is pressurized,lubricant is discharged from the lubricant discharge port 8, while theair supply pipe 16 is pressurized, lubricant in the lubricant tank 4 issucked into the plunger pump from the liquid suction port 3. A suctionspeed regulating knob 17 and a discharge speed regulating knob 18 areattached, respectively, to the air supply pipe 15 on the discharge sideand the air supply pipe 16 on the suction side.

FIG. 3 is a block diagram showing the construction of a control section.In the figure, reference numeral 20 denotes the control section forcontrolling operations of the aforesaid constituent components such thatthe rotating device 9, which is the rotary driving section, rotates therolling bearing 700 relative to the lubricant discharge ports 8 andstops it at a position where the lubricant discharge ports 8 are locateddirectly above the rolling bearing 700 based on a rolling elementdetection signal from the sensor 13, and that the prescribed liquidvolume discharge device 1 applies a lubricant to the interior of therolling bearing 700.

The control section 20 has a controller 21, a first amplifier 22, anelectromagnetic valve 23 and a second amplifier 24. A rolling elementdetection signal is inputted in the controller 21 which is outputtedfrom the sensor 13 when it detects that the rolling element 703 comes toa predetermined phase (an angular phase about the axial center). Inaddition, outputted from the controller 21 are a rotation controlsignal, an electromagnetic valve control signal and a vertical slidecontrol signal for the prescribed liquid volume discharge device 1. Therotation control signal is inputted in the first amplifier 22, theelectromagnetic valve control signal in the electromagnetic valve 23 andthe prescribed liquid volume discharge device vertical slide controlsignal in the second amplifier 24.

The first amplifier 22 is connected to a rotational driving motor 25 forrotationally driving the rotating table 11. A driving voltage signaloutputted from the first amplifier 22 is inputted in the rotationaldriving motor 25, whereby the rotational rotating motor 25 isrotationally controlled. In controlling the rotational driving of therotating table 11, the sensor 13 is positioned in advance such that aswitch, not shown, for the sensor 13 is switched on (ON) when the phaseof the rolling element 703 coincides with that of the lubricantdischarge port 8 (or they are put in a phase relation at a predeterminedangle). The rotational driving motor 25 is to be equipped with anencoder so that a feedback control may be carried out or an open-loopcontrol may be carried out by means of a stepping motor or the like. Inaddition, in the event a single application of lubricant is sufficient,the rotation may be stopped by simply turning on the switch, andtherefore in that case, there is no need to use the encoder.

The electromagnetic valve 23 is connected to the plunger drivingpneumatic cylinder 26 of the plunger main body 2, and the supplydirection of air to the plunger driving pneumatic cylinder 26 can bechanged over by controlling the switching of the electromagnetic valve23.

The second amplifier 24 is connected to a vertical driving motor 27 forsliding the prescribed liquid volume discharge device 1 vertically.Rotational motions of the motor 27 are converted into vertical motionsvia a feed screw. A driving voltage signal outputted from the secondamplifier 24 is inputted in the vertical driving motor 27, whereby thevertical driving motor 27 is rotationally controlled.

The phase regulation unit-includes the rotating device 9 as the rotarydriving section, the sensor 13 and the control section 20.

Next, an operation will be described in which a lubricant is applied tothe interior of the rolling bearing 700 by means of the prescribedliquid volume discharge device 1 which is constructed as describedabove.

The rolling bearing 700 to which a lubricant is to be applied is held atthe holding portion 12 of the rotating table 11 of the rotating device9, and thereafter, the rotating table 11 of the rotating device 9 isrotated by the rotational driving motor 25. Then, the rolling bearing700 is rotated together with the rotating table 11, and when the rollingelement 703 of the rolling bearing 700 is positioned directly below thelubricant discharge port 8, a rolling element detection signal isoutputted from the sensor 13, and the rolling element detection signalso outputted is then inputted in the controller 21, whereby therotational driving motor 25 is stopped. Following this, the verticaldriving motor 27 is driven to be rotated in one direction so as todescend the vertically slidable table, whereby the prescribed liquidvolume discharge device 1 is descended together with the verticallyslidable table until it is stopped at a preset lower end of the loweringtravel. The lower end is set in advance at a height where the lubricantdischarge port 8 is positioned sufficiently close to the rolling element703 (a state indicated by two-dot chain lines in FIG. 1).

When this state is produced, the electromagnetic valve 23 is controlledso as to be switched over by the controller 21, and the plunger of theplunger pump main body 2 of the prescribed liquid volume dischargedevice 1 is driven so that a lubricant 30 is discharged from thelubricating discharge ports 8 of the oil feed nozzle 6. In this state,since the lubricant discharge ports 8 are sufficiently close to therolling elements 703, the lubricant 30 adheres to the rolling elements703 and then flows into gaps, respectively, between the raceway surfaceof the outer race 701 of the rolling bearing 700 and the rolling element703, the raceway surface of the inner race 702 and the rolling element703, and the retainer 704 and the rolling element 703.

A lubricant application volume per rolling bearing is determined by acombination of a total of the inner race raceway surface area, the outerrace raceway surface area and the surface area of the rolling elementand the viscosity of the lubricant used.

In this embodiment, a plunger pump (model type: PM502) manufactured byUNICONTROLS (INC) is used, and also used as the oil supply pipe 7 is atubular nozzle having an outside diameter of equal to or less than 1.5mm and an inside diameter of substantially 0.2 mm to 1.0 mm. The lengthof the stroke of the plunger pump can be prescribed by a so-calledmicrometer type stopper, whereby the discharge volume of a lubricant cansuitably be prescribed. In addition to the liquid lubricant, a semisolidlubricant such as grease can also be used.

In this embodiment of the present invention, a lubricant applicationvolume was determined for each of various kinds of specifications(rolling element diameter, groove configuration or the like) of arolling bearing having an outside diameter of 8 to 13 mm, an insidediameter of 4 to 5 mm and a width of 2 to 4 mm. First, a test wascarried out for one of them to determine an appropriate lubricantapplication volume therefor, and thereafter a lubricant applicationvolume was determined through a proportional calculation of the totalsurface area based on the results of the test.

In the case of the rolling bearing (having an outside diameter of 8 to13 mm, an inside diameter of 4 to 5 mm and a width of 2 to 4 mm) in theaforesaid example, the lubricant application volume was determined inthe range of 0.8 to 2.4 μl (micro liters) It is preferable that thelubricant application volume is set not in the range such that thelubricant is dropped from the discharge port, in a state before thelubricant is applied to the rolling bearing, but in the range such thatthe lubricant is retained in the discharge port 8 by surface tension ofthe lubricant for preventing the splash of the lubricant, before thelubricant is applied to the rolling bearing.

When the application of the lubricant to the interior of the rollingbearing 700 is completed as described above, the discharge of thelubricant from the lubricant discharge port 8 is stopped, and thevertical driving motor 27 is then driven to be rotated in the otherdirection to thereby ascend the vertically slidable table, whereby theprescribed liquid volume discharge device 1 is ascended together withthis vertically slidable table to be returned to the initial state ofFIG. 1.

In this embodiment, the number of lubricant discharge ports 8 to bedisposed is set so as be equal to that of rolling elements 703 of therolling bearing 700 to be disposed, but the present invention is notlimited thereto, and the number of lubricant discharge ports 8 to bedisposed may be set so as to be smaller than that of rolling elements703 to be disposed and in addition, the lubricant maybe applied in aplurality of steps by changing the phase. Namely, for instance, there isprovided a method in which the number of lubricant discharge ports 8 tobe disposed is set to be a half the number of rolling elements 703 to bedisposed (for instance, four) and a single prescribed liquid volumedischarge device 1 is used, which method includes a first step wherein alubricant is applied to four rolling elements 703 at intervals of everytwo rolling elements and a second step wherein after the rolling bearing700 is rotated through 45 degrees, the lubricant is applied to theremaining four rolling elements 703.

Moreover, in this embodiment, the case is described where the singleprescribed liquid volume discharge device 1 is used for application ofthe lubricant, but the present invention is not limited thereto, and inparticular, in a case where the lubricant is applied in several stepsand where such a method is incorporated in an automated production line,in order to reduce the cycle time, for instance, in a case where theapplication of the lubricant is carried out in two steps, two prescribedliquid volume discharge devices 1 may be used. In this case, therotating device 9 having the holding portion 12 for the rolling bearing700 is constructed so as to travel along the production line.

Furthermore, in this embodiment, the lubricant is constructed so as tobe applied to all the rolling elements 703, but the lubricant is notnecessarily applied to all the rolling elements 703. For instance, thelubricant is applied only to a part of the rolling elements 703, andthereafter the outer race 701 and the inner race 702 are rotatedrelative to each other for running-in rotations, whereby the lubricantso applied can be transferred to the raceway surfaces of the outer andinner races 701, 702 as in case where the lubricant is applied to allthe rolling elements 703.

In addition, the number of lubricant discharge ports 8 to be disposedmay be set to be smaller than that of rolling elements 703 to bedisposed, but in this case, if the latter is too much larger than theformer, there is caused a possibility that the lubricant flows out toportions other than those actually needing lubrication, and therefore,an application volume per rolling element is reduced by applying thelubricant in a plurality of steps while-changing-the phase (in otherwords, a lubricant application volume per rolling element is reduced),as is described above, or if the application of the lubricant ispossible, the number of lubricant discharge ports 8 to be disposed ismade close (or equal) to that of the rolling elements 703 to bedisposed. In addition, in a case where the discharge volume of thelubricant is too large even if the number of lubricant discharge ports 8that are disposed is made close to that of rolling elements 703 that aredisposed, such a drawback can be dealt with by reducing the dischargevelocity (flow rate at the time of discharge) of the lubricant. In otherwords, the discharge velocity of the lubricant is set to match avelocity at which the lubricant penetrates into gaps between the rollingelement 703 and the raceway surface of the outer race 701, the rollingelement 703 and the raceway surface of the inner race 702, the rollingelement 703 and the retainer 704, the retainer 704 and the outer race701, and the retainer 704 and the inner race 702.

With an appropriate application volume of the lubricant, if thelubricant is applied using the aforesaid methods, there is no risk ofthe lubricant flowing out to portions other than those needinglubrication, the lubricant being thus applied to and held at onlyportions actually needing lubrication.

Since there is provided to the prescribed liquid volume discharge device1 a minimum discharge volume as a limit, in a case where the applicationvolume is lower than the minimum discharge volume, a method is adoptedin which a lubricant diluted with a solvent is discharged. In this case,it is needless to say that an application volume to be set is a volumeof the lubricant remaining after the solvent vaporizes.

Moreover, in this embodiment, the method is adopted in which after thelubricant discharge ports 8 are caused to approach the rolling elements7 sufficiently, a prescribed volume of lubricant is discharged from thelubricant discharge ports 8 and is transferred to the rolling elements703. The present invention, however, is not limited thereto. Forexample, an oil droplet is formed at a distal end of the lubricantdischarge port 8 by discharging the prescribed volume of lubricant fromthe lubricant discharge port 8 in such a manner as not to drop therefrombefore the lubricant discharging port 8 approaches the rolling elements703. It is preferable that the oil droplet is formed in the range ofsize such that the lubricant does not drop from the lubricant dischargeport 8, that is, that the oil droplet is retained in the lubricantdischarge port 8 by surface tension of the lubricant. Thereafter, thelubricant discharge ports 8 is allowed to approach the rolling elements703 so that the oil droplets at the lubricant discharge ports 8 arebrought into contact with the rolling elements 703, respectively,whereby the lubricant can be applied to the rolling elements 703.

In addition, in this embodiment, the case is described in which afterthe rolling elements 703 of the rolling bearing 700 to which thelubricant is to be applied are positioned directly below the oil feedpipes 7, the prescribed liquid volume discharge device 1 is lowered.But, if it is constructed such that an interference of the sensor 13with the oil feed nozzle 6 or the like is avoided, the prescribed liquidvolume discharge device 1 may be constructed so as to be loweredimmediately after the rolling bearing 700 has been attached to and heldat the holding portion 12 of the rotating device 9.

Moreover, in this embodiment, the rolling elements 703 of the rollingbearing 700 to which the lubricant is to be applied are set such thatthey are positioned directly below the oil feed pipes 7 when the sensor13 detects them. However, the rolling elements 703 of the rollingbearing 700 to which the lubricant is to be applied may not be set suchthat they are positioned directly below the oil feed pipes 7 when thesensor 13 detects them. That is, a rotational angle of the rotatingtable 11 of the rotating device 9 from a state that the sensor 13detects the rolling elements 703 to a position where the rollingelements 703 are positioned directly below the oil feed pipes 7 ismeasured in advance, and the rotational angle so measured is stored in astorage section of a rotation control device of the rotating device 9 asa compensation angle, whereby the rotating table 11 of the rotatingdevice 9 may be constructed so as to be stopped after it is rotatedthrough the compensation angle after the sensor 13 detects the rollingelements 703 of the rolling bearing 700 to which the lubricant is to beapplied.

Furthermore, in this embodiment, the sensor 13 is adapted to detect therolling elements 703 of the rolling bearing 700 to which the lubricantis to be applied, but if the phase of the rolling elements 703 when thesensor 13 detects is constant at all times, the sensor 13 may beconstructed so as to detect any other constituent component than therolling elements 703, for instance, the part of the retainer 704.

Moreover, in this embodiment, the prescribed liquid volume dischargedevice 1 is adapted to slide in the vertical directions, but the presentinvention is not limited thereto, and the rolling bearing 700 to whichthe lubricant is to be applied may be constructed so as to slide invertical directions.

In addition, in this embodiment, the motor is employed to slidevertically the prescribed liquid volume discharge device 1, but anyother means including, for instance, a pneumatic cylinder or the likemay be used to drive the device.

[Second Embodiment]

Next, referring to FIGS. 5A and 5B, a second embodiment of the presentinvention will be described below.

FIGS. 5A and 5B are side views showing the construction of a mainportion of a lubricant applying apparatus according to this embodiment,and the figure shows a state in which the prescribed liquid volumedischarge device 1 is descended. In addition, in FIGS. 5A and 5B, likereference numerals are given to constituent components like to thosedescribed in the aforesaid first embodiment shown in FIG. 1.

In this embodiment, what is different from the first embodimentdescribed above is that a single oil feed pipe 7 is provided on the oilfeed nozzle 6. As well as the first embodiment, the oil supply pipe 7 isa tubular nozzle having an outside diameter of equal to or less than 1.5mm and an inside diameter of substantially 0.2 mm to 1.0 mm.

According to this embodiment, the construction of the oil feed nozzle 6is simplified by employing the construction in which the single oil feedpipe 7 is provided on the oil feed nozzle 6, and moreover, the relativeposition control between the oil feed pipe 7 and the rolling elements703 of the rolling bearing 700 to which the lubricant is to-be appliedis made simpler than in the first embodiment described above.

Furthermore, since other constructions, functions and effectiveness ofthis embodiment are identical to those of the aforesaid firstembodiment, descriptions thereof will be omitted.

[Third Embodiment]

Next, referring to FIG. 6, a third embodiment will be described below.

FIG. 6 is a side view showing the construction of a main portion of alubricant applying apparatus according to this embodiment, and thefigure corresponds to FIG. 4 showing the above-described firstembodiment of the present invention. In addition, in FIG. 6, likereference numerals are given to constituent components like to thosedescribed in the above first embodiment shown in FIG. 1.

In this embodiment, what is different from the first embodiment is thatthe rolling elements 703 of the rolling bearing 700 are positioneddirectly below the lubricant discharge ports 8 using a mechanicalmethod, whereas in the first embodiment, the rotating device 9 and thesensor 13 are used for positioning the rolling elements 703 of therolling bearing 700 directly below the lubricant discharge ports 8.

Namely, as shown in FIG. 6, a concave engagement portion (engagementportion) 28 is formed in a lower face of the retainer 704 of the rollingbearing 700, and a convex engagement portion (engagement portion) 29 isformed on an upper face of a holding table 11 a having the holdingportion 12 for the rolling bearing 700, whereby the rolling elements 703of the rolling bearing 700 to which the lubricant is to be applied arepositioned directly below the lubricant discharge ports 8 through anengagement of the convex engagement portion 29 of the holding table 11 awith the concave engagement portion 28 of the retainer 704.

According to this embodiment, since the retainer 704 is constructed soas to be locked on the holding table 11 a at a predetermined phasethrough the engagement of the convex engagement portion 29 of theholding table 11 a with the concave engagement portion 28 of theretainer 704, the rolling elements 703 of the rolling bearing 700 towhich the lubricant is to be applied can be positioned directly belowthe lubricant discharge ports 8 with a simple construction.

In the case of this embodiment, if the lubricant can be applied in asingle step, there is no need to rotate the holding table 11 a. In otherwords, the rotating device 9 having he rotating table 11 is not neededand the holding table may only have to be constructed so as to beengaged and held as shown in FIG. 6. In this case, however, if thelubricant is applied by using a single prescribed liquid volumedischarge device 1 in a plurality of steps by changing the phase of therolling bearing, it is needless to say that the rotating device 9 andthe like are needed as a matter of fact.

In addition, in the case of this embodiment, although the concaveengagement portion 28 is formed in the retainer 704 of the rollingbearing 700 and the convex engagement portion 29 which is adapted to bebrought into engagement therewith is formed on the holding table 11 a,but the present invention is not limited thereto. For instance, if acrown-shaped retainer having convex and concave portions is used as theretainer, engagement portions may be provided on the holding table 11 ain such a manner as to be brought into engagement with those convex andconcave portions.

Since other constructions, functions and effectiveness of thisembodiment are identical to those of the aforesaid first embodiment,descriptions thereof will be omitted.

In addition, this embodiment may be constructed so as to be combinedwith the first embodiment (or a modified example thereof) or the secondembodiment (or a modified example thereof) both of which constitute thefeatures and constructions of this third embodiment.

[Fourth Embodiment]

Next, referring to FIG. 7, a fourth embodiment of the present inventionwill be described below.

FIG. 7 is a side view showing the construction of a lubricant applyingapparatus according to this embodiment and in the figure, like referencenumerals are given to constituent components like to those shown in FIG.1.

In this embodiment, what is different from the aforesaid firstembodiment is that the lubricant tank 4 is provided apart from theplunger pump main body 2.

The lubricant tank 4 of this embodiment is constructed so as to betightly closed, and the lubricant contained in the interior thereof canpneumatically be pressurized and sent out under pressure.

A filter 31 is connected to an output port of the lubricant tank 4, anda flexible tube 32 is disposed so as to connect the output port side ofthis filter 31 with the liquid suction port 3 of the plunger pump mainbody 2 in order that vertical movements of the plunger pump main body 2are not interrupted. This tube 32 is branched at a central portionthereof and a air vent cock 33 is connected between the branched tubes.In addition, in FIG. 7, reference numeral 34 denotes an air pressureregulator.

According to this embodiment, the frequency of refilling lubricant canbe reduced by increasing the capacity of the lubricant tank 4. Inaddition, a lubricant of a high degree of cleanness can be supplied tothe plunger pump main body 2. In other words, a lubricant of a highdegree of cleanness can be supplied to the rolling bearing.

[Fifth Embodiment]

Next, referring to FIGS. 8-11, a fifth embodiment of the presentinvention will be described below.

In this embodiment, a description will be given of an inspection methodfor inspecting whether or not the lubricant is discharged from the oilfeed pipe 7 with the discharge apparatus 1 of the second embodimentshown in FIG. 5. In the figures, like reference numerals are given toconstituent components like to the prior embodiments.

In this embodiment, as shown in FIGS. 8 and 9, a laser beam L₁ isirradiated from a laser beam projector (hereinafter, referred to brieflyas a projector) 115 to a discharge position of the lubricant, and in acase where the lubricant is applied, a reflected laser beam L₂ isreceived by a laser beam photoreceptor (hereinafter, referred to brieflyas a photoreceptor) 116, whereby a lubricant applied condition of therolling element 703, that is, whether or not the lubricant is accuratelydischarged to be applied to the surface of the rolling element 703 isinspected. To be more specific, in a case where the lubricant isaccurately discharged, as shown in FIG. 8, a lubricant droplet is formedby virtue of surface tension between the surface of the rolling element703 and the lubricant discharge port 8 of the oil supply pipe 7. Whenthis oil droplet is irradiated with the laser beam L₁, the reflectedlaser beam L₂ is caused to enter the photoreceptor 116 from the surfaceof the oil droplet. Then, the photoreceptor 116 generates a voltagesubstantially in proportion to the intensity of the laser beam received.

When the photoreceptor 116 receives the reflected laser beam L₂, even ifthe prescribed volume of the lubricant is not discharged and hence thereis formed no oil droplet, depending on an irradiating position of thelaser beam L₁, the reflected light may directly enter the photoreceptor116 from the surface of the rolling element 703. Then, irrespective ofno lubricant being discharged, it may be erroneously understood fromsuch detection of the reflected laser beam L₂ that the lubricant isproperly discharged. To cope with this, in this embodiment, mountingpositions of the projector 115 and the photoreceptor 116 are set suchthat an angle becomes as acute as possible which is formed between thelaser beam L₁ projected from the projector 116 and a perpendicular planeH perpendicular to an axis of the rolling bearing 700. Due to this, inorder that the laser beam does not interfere with the outer race of therolling bearing, the projector 115 is disposed such that the laser beamL₁ projected from the projector 115 is directed substantially in atangent direction of a pitch circle of a rolling element of the rollingbearing.

To be specific, as shown in FIG. 8, a projection angle α of the laserbeam projected to the rolling element 703 is set so as to become acuterelative to the horizontal plane H, for instance, an angle equal to orsmaller than 30 degrees. In addition, an angle formed between theprojector 115 and the photoreceptor 116 is set, as shown in FIG. 9, bydisposing the photoreceptor 116 at a position where the reflected laserbeam L₂ of a sufficient intensity can be obtained from the oil dropleton the rolling element 703.

In the case of a bearing of a small diameter, a minute volume oflubricant is injected, and in order to perform a precise injection, itis desirable that the lubricant discharge port 8 of the oil supply pipe7 is sufficiently close to the rolling element 703. Then, in order toirradiate the laser beam L₁ between the lubricant discharge port 8 andthe rolling element 703 which are disposed sufficiently-close to eachother, the spot diameter of the laser beam L₁ needs to be made minute.

Next, referring to FIG. 10, described below will be the construction ofa lubricant applied condition inspecting apparatus 120 according to theembodiment of the present invention.

Connected to a control section 125 for controlling the operations of thelubricant applied condition inspecting apparatus 120 in a generalizedfashion are a laser driving section 121 for driving and controlling theprojector 115 of the laser beam, a pump driving section 122 for drivinga plunger pump 2 for the discharge device 1 and a bearing race rotarydriving section 123 for rotating the bearing race of the rolling bearing700 such that the position of the rolling element 703 coincides with theposition of the lubricant discharge port 8 of the oil supply pipe 7.

In addition, the lubricant applied condition inspecting apparatus 120further includes a peak hold circuit 127 inputting an output signalgenerated from the photoreceptor 116 when the reflected laser beam isreceived thereby through reception of the reflected laser beam reflectedfrom the oil droplet of lubricant by the photoreceptor 116 and holdingthe peak level of the output signal when receiving the reflected laserbeam, and an OK/NG judgement circuit 128 for receiving the output signalfrom the peak hold circuit 127 so as to judge whether or not thelubricant is discharged. The control section 125 outputs a rest signalfor releasing the peak level held by the peak hold circuit 127 at antiming which will be described later.

Connected to this control-section 125 are a NG product discharge device148, a display 149, and an alarming device 150, whereby the controlsection 125 controls the NG product discharge device 148 such that itdischarges the bearing 147 based on a signal from the judgement circuit128. At this moment, the display 149 and the alarming device 150 areactuated selectively by the control section 125.

Next, a description will be given of an inspection method for inspectinga lubricant applied condition of the rolling bearing 700.

First, the rolling bearing 700 is mounted on a fixing jig, (not shown)of an applying apparatus, and a position regulation of the lubricantdischarge port 8 of the oil supply pipe 7 and the rolling element 703 ofthe rolling bearing 700 is carried out. Various methods can be conceivedas a method for this regulation, and for instance, one of them is aregulation method including the steps of rotationally driving the innerrace 702 by the bearing race rotational driving section 123 so as tochange the positions of the rolling elements 703, irradiating a laserbeam from the projector 115 as previously described by the laser drivingsection 121 and detecting the intensity of a reflected laser beam by thephotoreceptor 116 for regulation. According to this method, a rotationalposition where the intensity of the reflected laser beam is enhanced tobecome a peak coincides with a position where the laser beam isirradiated to the rolling element 703, and this position is spaced awaya certain distance from a position where the rolling element 703 isdisposed directly below the lubricant discharge port 8 of the oil supplypipe 7. This spaced away distance is determined by a positionalrelationship including the directions of the projector 115, thephotoreceptor 116 and the bearing 700. Therefore, a rotational angle ofthe inner race corresponding to that spaced away distance is measured inadvance and is then stored in the control device 125. With a furtherrotation through the stored angle from a rotational position where theintensity of the reflected laser beam becomes the peak, a state isproduced in which the rolling element 703 is disposed directly below thelubricant discharge port 8 of the oil supply pipe 7.

In this position regulation method, when the lubricant is applied to therespective balls one by one by moving them in that way, the regulationmay be performed every time the balls are moved with a view to having anaccurate regulation. In addition, if the number of rolling elements 703is known in advance, the position of the rolling elements 703 may simplybe set by detecting the position of only one of the rolling elements andusing an index rotation for the remaining rolling elements 703 in whichthey are rotated through a predetermined certain angle.

After the regulation of the rolling elements 703, since the peak levelis held in the peak hold circuit 127 by the reflected light from therolling element 703, in order to restore the initial voltage level, arest signal is outputted from the control section 125, and then adriving signal (a lubricant discharging operation signal) V₁ is suppliedfrom the control section 125 to the pump driving section 122 at a pointt₁ shown in FIG. 11, whereby the lubricant is discharged from thedischarge apparatus 1.

The discharge apparatus 1 adopts a-system for extruding the lubricant bydriving the plunger, and therefore there is caused a time lag between aninput of the discharging operation signal V₁ and an actual discharge ofthe lubricant from the lubricant discharge port 8. Then, when thelubricant is discharged from the lubricant discharge port 8 at a pointt₂, there is instantly caused a large variation in the output signal V₂from the photoreceptor 116.

When the voltage level of the output signal V₂ largely varies as shownin FIG. 11, the peak hold circuit 127 shown in FIG. 10 detects thisvariation in voltage level, and the output signal V₃ of the peak holdcircuit 127 varies from V_(L) to V_(H). The OK/NG judgement circuit 128judges whether or not the lubricant is discharged in response to thosetwo states of V_(H) and V_(L).

In a case where the lubricant is judged as being discharged properlybased on the judgement results from the OK/NG judgement circuit 28, thecontrol section 125 outputs a peak hold reset signal for resetting thevoltage level of the output signal set at V_(H) in the peak hold circuit127 to the initial state. In addition, the control section 125 rotatesthe inner race by the bearing race rotational driving section 123 so asto perform a position regulation of the following rolling element 703for discharging the lubricant thereto and inspecting the lubricantapplied condition thereof.

On the other hand, in a case where the discharge of the lubricant isjudged as abnormal, the control section 125 outputs an abnormal signalfor alarming, stops the application of the lubricant, stops the machine,or performs an NG discharge of the bearing under inspection as adefective, whereby it is possible to prevent a rolling bearing to whichthe lubricant is abnormally applied from being transferred out to a postprocess.

The aforesaid process is repeatedly performed until the lubricant isapplied to all the rolling elements 703.

Thus, in the method for inspecting the application of lubricantaccording to the present invention, the rolling element 703 isregistered directly below and close to the lubricant discharge port 8for discharging the lubricant, and thereafter the lubricant isdischarged onto the rolling element 703, while the laser beam isirradiated from the side thereof for detection of the existence of areflected laser beam from a prescribed direction. Then, the reflectedlight of the laser beam is generated only a short time period duringwhich the lubricant is discharged, but with the utilization of the peakhold circuit 127, a variation in the output signal from thephotoreceptor 116 can be detected with high sensitivity, whereby adetection with high sensitivity is performed without escaping even amomentary variation in the output signal.

In addition, since the projector 115 and the photoreceptor 116 areconstructed so as to be disposed separately from each other, it ispossible to enhance the degree of freedom of design in location ofequipment and regulation thereof.

According to the lubricant applied condition inspecting apparatusconstructed as described above, in the case of mass production ofrolling bearings in which the lubricant is injected into the interiorthereof, automatic total inspection can be carried out for every rollingbearing to inspect whether or not the lubricant is injected thereinto,whereby the quality and reliability of rolling bearings so produced canbe improved, while reducing the production costs.

Further, the projector 115 and the photoreceptor 116 are can be used asthe sensor of the first embodiment for performing the positioningfunction.

Since other constructions such as the discharge apparatus, functions andeffectiveness of this embodiment are identical to those of the aforesaidsecond embodiment, descriptions thereof will be omitted.

Of course, the lubricant applied condition inspecting apparatus of thisembodiment can be applied to any discharge apparatus of the first tofourth embodiments. In particular, in case that the lubricant appliedcondition inspecting apparatus is applied to the discharge apparatus ofthe first embodiment, the application and the inspection of thelubricant are simultaneously performed with respect to a plurality ofrolling elements 703 of the rolling member 700. As to the inspection ofa lubricant applied condition, since a substantially equal volume oflubricant is discharged from the respective oil supply pipes 7, thelubricant applied condition of all the balls can be grasped byinspecting only one of the balls for the lubricant applied condition. Inaddition, as described above, the reliability of inspection can beimproved by inspecting individually the rolling elements 703 throughirradiation of the laser beam to the rolling elements 703 one by one.Furthermore, the laser beam may be constructed so as to be irradiated tothe plurality of rolling elements 703 at one time for inspection, and inthis case, since a plurality of inspection systems are used forinspection, not only can the reliability of inspection further beimproved but also the inspection can be carried out far faster.

In this embodiment, the lubricant is discharged onto the rollingelements 703 of the rolling bearing, but on top of that method, thelubricant applied condition inspecting apparatus of this embodiment canbe applied to a discharge apparatus that the lubricant may beconstructed so as to be discharged onto the retainer between the rollingelements. In addition, as to the lubricant, on top of the liquidlubricant, a grease-like solid lubricant may equally be applicable.

[Sixth Embodiment]

Next, referring to FIG. 12, described below will be a sixth embodimentof the lubricant applied condition inspecting apparatus according to thepresent invention. This embodiment is characterized in that theprojector and the photoreceptor of the fifth embodiment are integratedinto one construction, and like reference numerals are given tofunctional components, whereby descriptions that would overlap previousones will be omitted.

In this embodiment, a laser sensor 131 is used in which the projectorand the photoreceptor are integrated. According to this construction,there-is no need of angle regulation of the laser beams L₁, L₂, in otherwords, no angle adjustment is needed which is set from the set positionsof the projector 115 and the photoreceptor 116. This simplifies largelythe assembling work of the lubricant applied condition inspectingapparatus and the construction of the entirety of the inspecting deviceas well. In addition, for instance, a laser projecting and receivingdevice LZ-155 manufactured by Keyence Corporation. may be used as theprojector 15 and the photoreceptor 16 of this embodiment.

This laser sensor 131 can be also used as the sensor 13 of the firstembodiment for-performing the positioning function.

[Seventh Embodiment]

Next, referring to FIGS. 13 and 14, described below will be a lubricantapplying system according to a seventh embodiment of the presentinvention, specifically, the another lubricant applied conditioninspecting apparatus.

FIG. 13 shows the construction of a lubricant applied conditioninspecting apparatus according to this embodiment, and FIG. 14 is ablock diagram showing a flow of signals for inspecting the lubricantapplied condition.

In this embodiment, an amine antioxidant is added into the lubricantwhich is excited with an ultraviolet ray so as to emit fluorescence.With the rolling bearing applied with such a lubricant, since thesurface applied with the lubricant emits fluorescence when irradiatedwith an ultraviolet ray, defective or non-defective with respect to theapplication of the lubricant can be judged by seeing whether or not thefluorescence is emitted from the surface. As the amine antioxidant foruse in this embodiment, for instance, IRGANOX L06 produced by ChibaSpecialty Chemicals (Inc) may be used.

Next, the construction of a lubricant applied condition inspectingapparatus 140 will be described below. This lubricant applied conditioninspecting apparatus includes a placing table 141 for securing therolling bearing 700 to which the lubricant is applied, a light shieldinghood 142 for preventing the rolling bearing 700 on the placing table 141from being exposed to external visible light, a black light bluefluorescent lamp 143 provided inside the light shielding hood 142 forirradiating a near ultraviolet ray to the rolling bearing 700 and avideo camera 144 for picking up an image of the rolling bearing 700 towhich the near ultraviolet ray is irradiated. Image data so picked upare constructed so as to be then inputted into a control section 146 viaan image processor 145 as shown in FIG. 14.

The black light blue fluorescent lamp 143 is a fluorescent lamp in whicha near ultraviolet irradiating fluorescent substance is coated inside aglass tube using a dark blue special filter which allows the nearultraviolet ray to transmit therethrough in an efficient fashion, andthe fluorescent lamp emits a near ultraviolet ray of a wave lengthranging 300 nm to 400 nm (with a peak wave length of 370 nm).

The black light blue fluorescent lamp 143 is formed in an annular shapeand an upper portion thereof is covered with a lamp cover 147 having areflection film formed on an internal surface thereof. The video camera144 has an image picking up device 144 a such as a CCD, a condensinglens 144 b and a infrared ray cut-off filter 144 c for cutting offnoise.

Next, a method for inspecting a lubricant condition according to thisembodiment will be described below.

The rolling bearing 700 to which the lubricant is applied is placed onthe placing table 141, and the black light blue fluorescent lamp 143 isturned on so as to irradiate the near ultraviolet ray to the rollingbearing 700. Then, an image of the rolling bearing 700 irradiated withthe near ultraviolet ray is picked up by the video camera 144. Since thelubricant emits fluorescence when the ultraviolet ray is receivedthereby, the image so picked up then is reflected as white on thesurface over which the lubricant is applied, while portions to which thelubricant is not applied do not emit any fluorescence and hence they arereflected as black on the picked up image. An image signal from thepicked up image is then inputted into the image processor 145 shown inFIG. 14.

In the image processor 145, the image signal so inputted is thenbinarization processed so that only white portions reflected by thefluorescence can be extracted. Then, the total surface area of the whiteportion is calculated and the calculated total surface area is thencompared with data on the area of the white portions set in advance. Asthe results of the comparison, if the calculated total surface area isequal to or larger than the set value, the lubricant applied conditionis judged as being good, and on the contrary, when it smaller than theset value, the condition is judged as being not good. The result of ajudgement on OK or NG is outputted as a signal to the control section146 connected to the image processor 145.

The control section 146 controls such that the rolling bearing 700 istransferred to a post process when an OK signal is inputted, while whenan NG signal is inputted, then the control section 146 controls suchthat the rolling bearing 700 is discharged as a defective and generatesan alarm.

If the black light blue fluorescent lamp 143 is kept turned on while theapplication of lubricant is being detected, the temperature of the lamp143 is increased and eventually emits infrared rays. When the infraredray so generated is reflected on the rolling bearing and enters the CCD144 a, electric charge is accumulated in the CCD 144 a and it appears inan output image signal Va as noise. To cope with this, in the presentembodiment, an infrared ray cut-off filter 144 c is provided on thevideo camera 144 so as to remove infrared rays. According to thisconstruction, there is no risk of noise appearing in the output imagesignal Va even if the detection of the application of lubricant isrepeatedly performed, thereby making it possible to perform accuratelubricant application detection in succession.

Since the lubricant applied condition detecting device 40 according tothe present embodiment can be incorporated in an automatic machine forapplying a lubricant to the rolling bearing 700, it is possible toinspect in line lubricant applied conditions of the total number ofrolling bearings. Then, in a case where no application of lubricant iscarried out for some reason or where there is happening a failure ofapplication of lubricant, the rolling bearing under inspection isdischarged from the aforesaid inspection line based on an NG signal fromthe application detecting device 140, or the machine is automaticallytemporarily stopped, whereby the rolling bearing judged as defective isprevented from being transferred to a post process. Consequently, mixingof a defective into rolling bearing products can be prevented, wherebyrolling bearings with high quality can be produced.

According to the present invention, as has been described heretofore,since lubricant can be applied easily and securely only to portions suchas the rolling elements inside the rolling bearing and the racewaysurfaces which actually need lubrication, the lubricant does not adhereto portions other than those which actually need lubrication such as theexternal side of the rolling bearing. Therefore, a required volume oflubricant is secured in the interior of the rolling bearing, whereas theexternal side of the rolling bearing is left sufficiently dry. Thus,this lubricant application are optimally suitable for use for anappartus such as a hard disk drive needing a high degree of cleanness inthe interior thereof, and there is also provided an advantage in which arolling bearing can be produced at low costs which can reduce the torqueand perform stabilization thereof.

Furthermore, there is provided an advantage in which a volume oflubricant to be applied to the rolling elements inside the rollingbearing can be controlled in an accurate fashion.

In addition, according to the method and apparatus for inspecting alubricant applied condition of a rolling bearing according to thepresent invention, the laser beam is irradiated toward between thedischarge port of the lubricant discharge device and the rollingbearing, and the reflected laser beam reflected by the lubricant when itis discharged from the discharge port is received by the photoreceptordevice disposed on the optical axis of the reflected laser beam, wherebywhether or not the lubricant is applied to the rolling bearing isinspected based on the output from the photoreceptor device. Thisprevents a rolling bearing from failing to be properly applied with thelubricant from being transferred to a post process, whereby not only canthe reliability of the rolling bearing itself be improved but also thereliability of equipment using that rolling bearing can be preventedfrom being deteriorated.

While only certain embodiments of the invention have been specificallydescribed herein, it will apparent that numerous modification may bemade thereto without departing from the spirit and scope of theinvention.

The present disclosure relates to the subject matter contained inJapanese patent application Nos. Hei.10-370097 filed on Dec. 25, 1999and Hei.11-161260 filed on Jun. 8, 1999 which are expressly incorporatedherein by reference in its entirety.

What is claimed is:
 1. A method for applying a lubricant to a rollingbearing, comprising the steps of: preparing a prescribed liquid volumedischarge device having at least one discharge port so that saiddischarge port and a holding table are relatively movable in a verticaldirection in an automated production line; disposing said rollingbearing on said holding table; relatively positioning said rollingbearing with respect to said discharge port so that said discharge portis located directly above and sufficiently close to a rolling element ofsaid rolling bearing; and transferring a prescribed amount of saidlubricant from said discharge port to said rolling element in an oildroplet form, to thereby apply said lubricant to the interior of saidrolling bearing.
 2. A method according to claim 1, wherein saiddischarge port comprises a plurality of discharge ports, the number ofwhich is equal to the number of said rolling elements of said rollingbearing.
 3. A method according to claim 1, wherein said discharge porthas been treated with an oil repellent treatment.
 4. A method accordingto claim 1, wherein the application amount of the lubricant per rollingbearing is set in the range of 0.8 to 2.4 μl.
 5. The method according toclaim 1, wherein said rolling bearing is located directly above thedischarge port by disposing said rolling bearing on the holding tablehaving a convex engagement portion.
 6. A method for applying a lubricantto a rolling bearing, comprising the steps of: disposing a rollingbearing on a rotating table rotatable in response to a rotation of amotor on an automated production line; rotating said rotating tableabout a center axis of said rolling bearing as a rotation axis;detecting a position of a rolling element of said rolling bearing bymeans of a sensor; stopping the rotation of said rolling bearing whensaid sensor detects the position of said rolling element; relativelypositioning at least one lubricant discharge port with respect to saidrolling element so that said lubricant discharge port is located abovesaid rolling element; transferring a prescribed amount of said lubricantfrom said discharge port to said rolling element so that lubricant isapplied to a gap between a raceway surface of a bearing ring of saidrolling bearing and said rolling element, a retainer and said rollingelement in an oil droplet form.
 7. A method according to claim 6,wherein said discharge port comprises a plurality of discharge ports,the number of which is equal to the number of said rolling elements ofsaid rolling bearing.
 8. A method according to claim 6, wherein saiddischarge port has been treated with an oil repellent treatment.
 9. Amethod according to claim 6, wherein the application amount of thelubricant per rolling bearing is set in the range of 0.8 to 2.4 μl. 10.The method according to claim 6, wherein said rotating table is stoppedin response to a rolling element detection signal outputted from asensor when said sensor detects a predetermined phase that the dischargeport is positioned above the rolling element.
 11. A method for applyinga lubricant to a rolling bearing having a crown-shaped retainer in anautomated production line, comprising the steps of: preparing aprescribed liquid volume discharge device having at least one dischargeport; locating said discharge port directly above and sufficiently closeto a rolling element of said rolling bearing from a side of the rollingbearing where the rolling element projects through the crown-shapedretainer; and transferring a prescribed amount of said lubricant fromsaid discharge port to said rolling element in an oil droplet form, tothereby apply said lubricant to the interior of said rolling bearing.12. A method according to claim 11, wherein said discharge portcomprises a plurality of discharge ports, the number of which is equalto the number said rolling elements of said rolling bearing.
 13. Amethod according to claim 11, wherein said discharge port has beentreated with an oil repellent treatment.
 14. A method according to claim2, wherein the application amount of the lubricant per rolling bearingis set in the range of 0.8 to 2.4 μl.